Refraction of light through\u00a0glass slab<\/a><\/li>\n<\/ul>\nSome Associated Terms<\/strong><\/p>\n\nTransparent surface:<\/strong> The plane surface which refracts light, is called transparent surface. In diagram, XY is the section of a plane transparent surface.<\/li>\nPoint of incidence:<\/strong> The point on transparent surface, where the ray of light meets it, is called point of incidence. In diagram, Q is the point of incidence.<\/li>\nNormal:<\/strong> Perpendicular drawn on the transparent surface at the point of incidence, is called normal. In diagram, N1<\/sub>QN2<\/sub> is the normal on surface XY.<\/li>\nIncident ray:<\/strong> The ray of light which strikes the transparent surface at the point of incidence, is called incident ray in diagram PQ is the incident ray.<\/li>\nRefracted ray:<\/strong> The ray of light which travels from the point of incidence into the other medium, is called refracted ray. In diagram, QR is the refracted ray.<\/li>\nAngle of incidence:<\/strong> The angle between the incident ray and the normal on the transparent surface at the point of incidence, is called the angle of incidence. It is represented by the symbol i. In diagram, angle PQN1\u00a0<\/sub>is the angle of incidence.<\/li>\nAngle of refraction:<\/strong> The angle between the refracted ray and the normal on the transparent surface at the point of incidence, is called angle of refraction. It is represented by symbol r. In diagram angle RQN2<\/sub> is the angle of refraction.<\/li>\nPlane of incidence:<\/strong> The plane containing the normal and the incident ray, is called plane of incidence. For the diagram, plane of book page is the plane of incidence.<\/li>\nPlane of refraction:<\/strong> The plane containing the normal and the refracted ray, is called plane of refraction. For the diagram, plane of book page is the plane of refraction.<\/li>\n<\/ol>\nRefraction of Light<\/strong><\/p>\n <\/p>\n
\nFigure shows how light rays pass through a glass block. From the figure:\n\nWhen a light ray (X) is incident normal<\/strong> (\u2220i = 0) to the boundary of the media (air to glass), it travels straight on without being bent.<\/li>\nWhen a light ray (Y) is incident at an acute angle<\/strong> to the boundary of the media, the light ray is bent or refracted.<\/li>\nThe light ray bends towards the normal<\/strong> when it travels from a less dense medium (air) to a denser medium (glass).<\/li>\nThe light ray bends away from the normal<\/strong> when it travels from a denser medium (glass) to a less dense medium (air).<\/li>\nThe angle of refraction (\u2220r) is always smaller than the angle of incidence (\u2220i) when light travels from a less dense medium<\/strong> to a denser medium<\/strong>.<\/li>\nIn the case of ray Y, the emergent ray<\/strong> is in the same direction as the incident ray<\/strong> but is laterally displaced<\/strong>. This is due to the two boundaries of the media, where the refractions occurred, being parallel to each other and that the refractions bend the ray equally and in opposite directions.<\/li>\n<\/ul>\n<\/li>\nThere is another interesting phenomenon which you can observe from Figure. At point A, ray Y travels from air to glass with an angle of incidence, i and an angle of refraction, r. At point B, ray Y travels from glass to air with an angle of incidence, r and an angle of refraction, i. It can be said that the ray, at point B, is travelling the exact same path as compared to point A, but in the opposite direction. This is the principle of reversibility of light<\/strong>.<\/li>\nRefraction of light<\/strong> is the bending of a light ray at the boundary<\/strong> as it travels from one medium to another.<\/li>\nAny substance that a light ray travels through is called a medium<\/strong>.<\/li>\nA medium, which is optically less dense or denser, has no connection with the formula, \nDensity = Mass\/Volume It is related only to the speed of light that travels through it. (All references to less dense and denser medium in this chapter is taken to mean optically less dense or denser.)<\/li>\n The more optically dense a medium is, the slower light travels through it.<\/li>\n A light ray travels much slower in a denser medium. When a light ray travels from one medium to another, its speed changes. The change in speed of the light ray causes it to change its direction.<\/li>\n The effect of refraction can also be explained by using the analogy of a car moving onto a sandy road as shown in Figure. \n <\/li>\n As one of the front wheels of the car hits the sand, it slows down while the other wheel keeps going at its original speed. This will cause the direction of the car to change. The new direction of the car will be closer to the normal.<\/li>\n<\/ul>\nLaws of Refraction of Light<\/strong><\/h2>\nFirst Law: <\/strong>\u00a0The incident ray, the normal to the transparent surface at the point of incidence and the refracted ray, all lie in one and the same plane. \nSecond Law :<\/strong> The ratio of sine of angle of incidence to the sine of the angle of refraction is constant and is called refractive index of the second medium with respect to the first medium. \n\\(\\frac{\\text{sin i}}{\\text{sin r}}=\\text{ }\\!\\!\\mu\\!\\!\\text{ }\\)<\/p>\n<\/h3>\n <\/p>\n","protected":false},"excerpt":{"rendered":"
What is Refraction of Light When a spoon is immersed into a glass of water, the spoon appears bent or broken as shown in Figure (a). When a part of the word PHYSICS is covered with a glass slab as shown in Figure (b), the covered letters appear displaced. The two situations described are perceptions … Read more<\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[404],"tags":[581,579,580],"yoast_head":"\nWhat is Refraction of Light - CBSE Library<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n